The present invention relates to an electrical connector; and, more particularly, to a modular jack of an electrical connector implementing a low crosstalk.
A communications terminal used in an office or home is electrically connected to an outdoor transmission cable via an electrical connector, which usually includes a modular jack and a plug. Though a four-pin connector has been widely used for the communications terminal, an eight-pin connector is now being developed to satisfy the need for a high transmission speed. Telecommunication Industry Association (TIA) and Electronic Industry Association (EIA) of U.S. are specifying Category 6, a new industrial specification, to keep up with a rapid development of communication parts including the eight-pin connector.
In a transmission cable, each pair of lines forms a signal pair to transmit a specific electrical signal. If a signal pair transmitting a first signal is adjacent to another pair transmitting a second signal, a capacitive coupling and an inductive coupling are induced between the first and the second signal, thereby causing an error in the signals. Such an electromagnetic interference between two adjacent signals is referred to as a crosstalk.
As shown in FIG. 1, an insert 2 of a conventional eight pin modular jack (not shown) includes an insert housing 4 and eight insert conductors xe2x80x9cR1xe2x80x9d to xe2x80x9cR4xe2x80x9d and xe2x80x9cT1xe2x80x9d to xe2x80x9cT4xe2x80x9d. The insert conductors xe2x80x9cR1xe2x80x9d to xe2x80x9cR4xe2x80x9d and xe2x80x9cT1xe2x80x9d to xe2x80x9cT4xe2x80x9d are arranged to run parallel to each other on one plane while maintaining a constant pitch therebetween. Portions of the insert conductors are embedded in the insert housing 4 serving to maintain relative positions thereof.
Such a single level arrangement of the insert conductors causes significant crosstalks both inside and outside the insert housing 4. Therefore, an electrical connector adopting the conventional modular jack can hardly satisfy specifications of Category 6.
In FIG. 2, there is illustrated a schematic arrangement of the conventional insert conductors xe2x80x9cR1xe2x80x9d to xe2x80x9cR4xe2x80x9d and xe2x80x9cT1xe2x80x9d to xe2x80x9cT4xe2x80x9d in order to explain the crosstalks therebetween, herein only a few capacitive coupling components are depicted for the sake of simplicity.
In the drawing, a first conductor xe2x80x9cR1xe2x80x9d and a second conductor xe2x80x9cT1xe2x80x9d form a first signal pair to transmit a first signal; a fourth conductor xe2x80x9cT2xe2x80x9d and a fifth conductor xe2x80x9cR2xe2x80x9d form a second signal pair for a second signal; a third conductor xe2x80x9cR3xe2x80x9d and a sixth conductor xe2x80x9cT3xe2x80x9d form a third signal pair for a third signal; and a seventh conductor xe2x80x9cR4xe2x80x9d and an eighth conductor xe2x80x9cT4xe2x80x9d form a fourth signal pair for a fourth signal. The second conductor xe2x80x9cT1xe2x80x9d and the third conductor xe2x80x9cR3xe2x80x9d are adjacent to each other and transmit different signals, i.e., the first signal and the third signal, respectively. Therefore, a strong electromagnetic coupling is induced between the first signal of the second conductor xe2x80x9cT1xe2x80x9d and the third signal of the third conductor In other words, a first capacitance xe2x80x9cC13xe2x80x9d is induced between the first conductor xe2x80x9cR1xe2x80x9d and the third conductor xe2x80x9cR3xe2x80x9d while a second capacitance xe2x80x9cC23xe2x80x9d is induced between the second conductor xe2x80x9cT1xe2x80x9d and the third conductor xe2x80x9cR3xe2x80x9d. The second capacitance xe2x80x9cC23xe2x80x9d is larger than the first capacitance xe2x80x9cC13xe2x80x9d (C23 greater than C13), because the capacitance is inversely proportional to a distance between two conductors and the third conductor xe2x80x9cR3xe2x80x9d is closer to the second conductor xe2x80x9cT1xe2x80x9d than the first conductor xe2x80x9cR1xe2x80x9d is. The above-explained capacitance difference causes an electrical potential difference between the second conductor xe2x80x9cT1xe2x80x9d and the third conductor xe2x80x9cR3xe2x80x9d, thereby increasing the capacitive coupling of the first signal of the second conductor xe2x80x9cT1xe2x80x9d and the third signal of the third conductor xe2x80x9cR3xe2x80x9d.
Further, a third capacitance C16 is induced between the first and sixth conductor xe2x80x9cR1xe2x80x9d and xe2x80x9cT3xe2x80x9d. However, because the sixth conductor xe2x80x9cT3xe2x80x9d is located relatively very far away from the first conductor xe2x80x9cR1xe2x80x9d, the third capacitance C16 is very small and an effect thereof can be disregarded.
Like the second and the third conductor xe2x80x9cT1xe2x80x9d and xe2x80x9cR3xe2x80x9d, if two conductors are respectively involved with different signal pairs but electromagnetically coupled, they are referred to as a crosstalk pair. The crosstalk mainly occurs between the conductors of the crosstalk pairs, such as xe2x80x9cT1-R3xe2x80x9d, xe2x80x9cR3-T2xe2x80x9d, xe2x80x9cR2-T3xe2x80x9d, and xe2x80x9cT3-R4xe2x80x9d.
Though the previous explanation is focused on the first to the third capacitances xe2x80x9cC13xe2x80x9d, xe2x80x9cC23xe2x80x9d and xe2x80x9cC16xe2x80x9d, other capacitances including a fourth to a sixth capacitances xe2x80x9cC12xe2x80x9d, xe2x80x9cC36xe2x80x9d and xe2x80x9cC26xe2x80x9d are also induced among the insert conductors. A detailed explanation about the fourth to the sixth capacitances, however, is omitted for the sake of simplicity.
The U.S. Pat. No. 5,299,956 teaches a method for preventing the crosstalk. In the method in accordance with the above-mentioned U.S. patent, an opposite electromagnetic coupling is induced to cancel the inductive or capacitive coupling. With reference to FIG. 3, the purport of the U.S. Pat. No. 5,299,956 will be explained.
As shown, a first signal pair xe2x80x9cS1xe2x80x9d includes a first tip conductor xe2x80x9cT1xe2x80x9d and a first ring conductor xe2x80x9cR1xe2x80x9d while a second signal pair xe2x80x9cS2xe2x80x9d includes a second tip conductor xe2x80x9cT2xe2x80x9d and a second ring conductor xe2x80x9cR2xe2x80x9d. In a first portion xe2x80x9cZ1xe2x80x9d, the second tip conductor xe2x80x9cT2xe2x80x9d and the second ring conductor xe2x80x9cR2xe2x80x9d are disposed adjacent to the first ring conductor xe2x80x9cR1xe2x80x9d and the first tip conductor xe2x80x9cT1xe2x80x9d, respectively. In a second portion xe2x80x9cZ2xe2x80x9d, however, positions of the second tip and the second ring conductor xe2x80x9cT2xe2x80x9d and xe2x80x9cR2xe2x80x9d are interchanged with each other, such that the second ring conductor xe2x80x9cR2xe2x80x9d and the second tip conductor xe2x80x9cT2xe2x80x9d are disposed adjacent to the first ring conductor xe2x80x9cR1xe2x80x9d and the first tip conductor xe2x80x9cT1xe2x80x9d, respectively.
In the above-described configuration, a first crosstalk occurs between the first and the second signal pair xe2x80x9cS1xe2x80x9d and xe2x80x9cS2xe2x80x9d in the first portion xe2x80x9cZ1xe2x80x9d while a second crosstalk occurs therebetween in the second portion xe2x80x9cZ2xe2x80x9d. Because of the above-mentioned interchange of positions in the second portion xe2x80x9cZ2xe2x80x9d, the first crosstalk and the second crosstalk have opposite phases, thereby canceling each other.
That is to say, first inductive and the first capacitive coupling induced in the first portion xe2x80x9cZ1xe2x80x9d, and second inductive and second capacitive couplings induced in the second portion xe2x80x9cZ2xe2x80x9d have phases opposite to each other. Accordingly, the first inductive and the first capacitive coupling are canceled by the second inductive and the second capacitive coupling, such that a total crosstalk is reduced.
The method in accordance with the prior art can provide a simple configuration for a low crosstalk electrical connector by way of simultaneously canceling each of the capacitive coupling and the inductive coupling in the same portion. For the same reason, however, at least one of the capacitive coupling and the inductive coupling cannot be wholly canceled and a considerable amount of the crosstalk still remains.
The crosstalk cannot be actually reduced below a level of xe2x88x9246 dB even if the above-explained method is employed, if the transmission frequency of signal is around 250 MHz. That is to say, though a higher transmission frequency is required as the data transmission speed increases, the method in accordance with the prior art can rarely satisfy newly required specifications.
It is, therefore, an object of the present invention to provide a modular jack for an electrical connector that implements a low crosstalk for transmitting high frequency signals.
In accordance with one aspect of the invention, a preferred embodiment of the present invention provides a modular jack for a low crosstalk electrical connector, the jack including: a housing; a first signal pair passing through the housing and including a first conductor and a second conductor, a first imaginary plane containing the first and the second conductor; and a second signal pair passing through the housing and including a third conductor and a fourth conductor, a second imaginary plane containing the third and the fourth conductor, which are bent at least once to cross each other inside the housing, wherein the first and the second imaginary plane form a first angle of 80 to 90 degrees inside the housing before the crossing of the third and the fourth conductor while the first and the second imaginary plane form a second angle of 0 to 10 degrees inside the housing after the crossing thereof.
Another preferred embodiment of the present invention provides an insert of a crosstalk reducing modular jack, the insert including: an upper housing; a lower housing joined with the upper housing, the upper and the lower housing being symmetrical to each other with respect to a contact surface therebetween; an upper set including a first to a fourth tip conductor passing through the upper housing and being arranged on a plurality of levels, the third tip conductor having a first and a second protrusion protruded toward the second and the fourth tip conductor, respectively; and a lower set positioned under the upper set, the lower set including a first to a fourth ring conductor passing through the lower housing and being arranged on a plurality of another levels, the second ring conductor having another first and another second protrusion protruded toward the first and third ring conductor, respectively; a first air space interposed between the upper and the lower set; a second air space surrounding a portion of the first tip conductor inside the upper housing; and a third air space surrounding a portion of the fourth ring conductor inside the lower housing.
In accordance with another aspect of the invention, another preferred embodiment of the present invention provides a low crosstalk connector including: a first portion where an inductive coupling and a capacitive coupling are induced between adjacent lines, each independently transmitting a signal; a second portion where capacitances induced between the adjacent lines are selectively compensated to reduce the capacitive coupling; and a third portion where an opposite inductive coupling is induced between the adjacent lines to cancel the inductive coupling, wherein the inductive coupling of the second portion is minimized while the opposite inductive coupling of the third portion is maximized.